This project proposes studies measuring the electrically evoked auditory brainstem response (EABR) and the electrically evoked whole nerve action potential (EAP). We propose to make measurements of the threshold and growth of response with stimulus level, but will also emphasize temporal response measures such as recovery from refractory state. Our previous work has demonstrated that these measures are sensitive to degenerative changes in the auditory system and may also be related to perception of speech through the implant. We propose here to use these and other electrophysiological and psychophysical measures to address issues regarding fitting strategies in cochlear implant users. We hypothesize that the information that we gain through electrophysiological and psychophysical testing of individual cochlear implant users will allow us to choose more appropriate speech processing algorithms thereby maximizing performance with the device. We will evaluate several ways in which the programming of the speech processor may be adjusted to increase performance on speech perception tasks in conjunction with Project #1 - Audiology and Speech Processing. We will also evaluate the extent to which physiological tests may serve as a basis for choosing particular speech stimuli to use in auditory training asks in conjunction with Project #5 - Speech and Language and to choose particular stimuli for use in music training tasks in conjunction with Project 3 - Music Perception.